1. Field of the Invention
The invention relates to a blood lancing device for pricking a person's skin to obtain a drop of blood.
2. Description of the Related Art
Many medical procedures require a relatively small sample of blood, in the range of 5-50 μl. Normally such a sample is obtained by lancing or piercing the skin at a selected location, such as a finger, to enable collection of 1 or 2 drops of blood. With the advancement of home use tests such as self monitoring of blood glucose, there is a requirement for a simple and safe procedure which can be performed by a person needing such tests.
Lancets in conventional use generally have a rigid body and a sterile pricking element, for example a needle, which protrudes from one end of the rigid body to pierce the skin, thereby enabling the collection of the blood sample. The collected blood is then transferred to a test device or a collection device. Blood is most commonly taken from fingertips, where the supply is generally excellent. However, blood can also be taken from alternate sites, such as earlobes and limbs.
To reduce the anxiety of piercing the skin and to guarantee a reproducible penetration result, many spring-loaded lancing devices have been developed. For example, a lancing device disclosed in European Patent No. 2050393 includes a mode-switch member for switching the lancing device between a cocking state, wherein operation of a loading member provides a cocking of a lancet holder, and a firing state, wherein further operation of the loading member provides an ejection of a lancet placed in the lancet holder.
The abovementioned operations of the loading member need to be done manually. However, the size of such a lancing device is relatively small, so that these manual operations are difficult to be performed on the miniature lancing device.
In another conventional lancing device disclosed in European Patent No. 0668049, before firing, a drive spring is compressed such that a biasing force of the drive spring is sufficient to cause a plunger to strike and drive a lancet into a user's finger. As such, safety can be promoted. However, many manual operations are still required during the lancing process.
In yet another conventional lancing device disclosed in U.S. Pat. No. 4,577,630, a mechanical trigger mechanism can be activated by a contact pressure between the patient's skin and the mechanical trigger mechanism.
In a single-use skin pricking device disclosed in European Patent No. 1247489, a trigger is releasably coupled to a lancet such that movement of the trigger in a first direction moves the lancet in a direction to compress a biasing means, and then causes release of the lancet from the trigger whereby the biasing means drives the lancet in a second direction substantially opposite to the first direction.
In European Patent No. 1755456, a lancet device includes a housing and a lancet structure having a puncturing element. The lancet structure is disposed within the housing and is adapted for movement between a retaining or pre-actuated position where the puncturing element is retained within the housing, and a puncturing position where the puncturing element extends through a forward end of the housing. The lancet device further includes a drive spring disposed within the housing for biasing the lancet structure toward the puncturing position, and a retaining hub retaining the lancet structure in the retaining position against the bias of the drive spring. The retaining hub includes a pivotal lever in interference engagement with the lancet structure. An actuator within the housing pivots the lever, thereby moving the lancet structure toward the rearward end of the housing to at least partially compress the drive spring, and releasing the lever from interference engagement with the lancet structure. Such a lancet device is disposable after a single use, and thus is suitable for hospital applications. However, it is necessary for a diabetic patient to carry a plurality of the disposable lancet devices, thereby resulting in inconvenience during use.
In skin pricking devices disclosed in WO 2008/009985, WO2010/098531, and European Patent No. 1204372, a spring can be preloaded prior to assembly of the device. However, these devices are al so disposable after a single use, and are operated by manual firing. Hence, it is desirable that a plurality of skin pricking operations can be performed by repeated depressions of the lancing device.